The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Internal combustion engines combust an air and fuel mixture within cylinders to drive pistons, which produces drive torque. In some types of engines, air flow into the engine may be regulated via a throttle. The throttle may adjust throttle area, which increases or decreases air flow into the engine. As the throttle area increases, the air flow into the engine increases. A fuel control system adjusts the rate that fuel is injected to provide a desired air/fuel mixture to the cylinders and/or to achieve a desired torque output. Increasing the amount of air and fuel provided to the cylinders increases the torque output of the engine.
Combustion of an air/fuel mixture within a cylinder begins when a spark plug generates spark within the cylinder. The mass fraction of fuel burned during a combustion event may be referred to as mass fraction burned (MFB). Various parameters for where various MFBs occur may be used to evaluate how fast the combustion event occurs. For example, a crankshaft angle (CA) where 50 percent of a mass of fuel has been burned during a combustion event is referred to as CA50.